Survival and DNA Breakdown after Gamma-irradiation in Synchronously-growing Escherichia Coli B

Summary

To determine whether the extent of radiation-induced DNA degradation is influenced by the process of cell fission or by the commencement of DNA replication cycle, experiments with synchronously-growing E. coli B bacteria have been performed. The results show that the extent of DNA breakdown is the same throughout the cell-division cycle, indicating that DNA degradation is related neither to cell fission nor to the DNA replication cycle. Certain variations in survival, however, occur during the cycle, and they are well correlated with the DNA content per cell. This suggests that a recovery mechanism, which depends on the process of genetic recombination, is responsible for fluctuations in sensitivity.